This U.S. election will shape the future of Europe and the trans- atlantic West.

If President Bush is reelected, many Europeans will try to make the European Union a rival superpower to the United States.

Led by French President Jacques Chirac, they will find the main justification for further European integration in counterbalancing what they see as irresponsible, unchecked American power. In the great European argument between Euro-Gaullists and Euro-Atlanticists, these Euro-Gaullists will be strengthened. The temptation for Europe to define itself as Not America will be increased. All this at a formative moment when an enlarged European Union is hoping to give itself a new constitution and work out what it wants to be.

Specifically, even fewer of the European states will be ready to help pull Washington's irons out of the fire in Iraq. Poland has already said it will follow Spain out of that firestorm; Tony Blair's position will be more embattled than ever. Meanwhile, Iran seems likely to precipitate the next crisis of the West. If a second Bush administration were to unilaterally threaten the use of force to prevent Iran developing a nuclear weapons capability, one can imagine the furious reaction on the streets of Europe.

Yet the Iranian regime, unlike Saddam Hussein, probably is close to developing a nuclear weapons capability -- and Europe's soft diplomacy has been no more effective in preventing it than U.S. huffing and puffing. Only combined action stands a chance.

Even more important, in the longer term, is China. Chirac has been pursuing a shameless policy of wooing China, for French economic advantage and to poke Washington in the eye. He has endorsed Beijing's position on Taiwan and said the E.U. embargo on arms exports to China should be lifted. This raises the grotesque prospect of European weapons being pointed at American warships in the Taiwan Strait. But of course it's not France that is calling the shots here. In the 1970s, Henry Kissinger played the China card against the Soviet Union. Today, China is playing the European card against the United States.

The Euro-Gaullist attempt to create a rival European superpower would be catalyzed by the advent of a second Bush administration. It would not, however, succeed. The forces of Euro-Atlanticism are still much too strong, especially in an enlarged European Union of 25 member states. A second Bush administration would find plenty of opportunities to do what it has done already in the past few years: divide and rule. The result would be a divided Europe in a still more divided West.

If, however, Americans choose Sen. John F. Kerry as their 44th president, we will have a chance of reconstructing the transatlantic West on a new basis. In Europe, Kerry will enjoy a huge opening bonus simply because he is not George W. Bush. His offer of working with allies will be greeted with open arms. Skeptics say the difference between the two candidates' approaches is style, not substance, but in this relationship, style is substance. The difference between unilateralism and multilateralism is all about how you do it, not what you do. Half the European objections to Bush's policy concern the how, not the what. Electing Kerry would encourage the silent majority of Euro-Atlanticists in Europe to speak up. Moreover, Kerry can credibly say he wants a united Europe as a strong partner of the United States, whereas no one in Europe would now believe Bush even if he said it.

The difficulties are still immense. Germany and France won't send troops to Iraq. On Iran, Europe needs to get tougher while America needs to get smarter. As the largest emerging market in the world, China will find many more chances for divide-and-rule between export-hungry Western democracies.

So we may still fail. But there is a chance.

I think it important to make clear the position from which I write. I love America, spend part of each year at a great American university and believe passionately that it is possible to be both pro-European and pro-American. I have never belonged to any British political party, let alone an American one. As a contemporary historian, I conclude that some Republican presidents have done great things for Europe.

Ronald Reagan's dramatic turn from arms race to detente, in response to the emergence of Mikhail Gorbachev, was one such. The current president's father, George H.W. Bush, made the peaceful liberation of Central Europe possible by his wise and mature statecraft. But not this Bush, not this time.

In any sober analysis, the chances of the world's two largest assemblages of the rich and free being able to work together to confront the coming great global challenges will be better with a President Kerry. And only if America and Europe work together can we unfold, for the rest of the world, the transforming power of liberty.

The writer is professor of European studies at Oxford University and a senior fellow at the Hoover Institution at Stanford University. His next book, "Free World: America, Europe and the Surprising Future of the West," will be published next month.